DESCRIPTION (adapted from the investigator?s abstract): This core will provide statistical advice and recommendations to all projects. It will facilitate the application of several novel statistical methods for combining data across multiple domains including recursive partitioning, implemented as tree-structured regression, grade-of-membership models and person-centered analysis of longitudinal data. This core will provide tutorials to the Center staff and trainees conducted by Drs. Singer and Hauser in the conceptual underpinnings of the various statistical approaches that are recommended. This core will also provide data management services for the projects.